Node: Querying Points, Next: , Previous: Copying Points, Up: Point Reference


bool is_identity (void) inline function
Returns true if transform is the identity Transform.

Transform get_transform (void) const inline function
Returns transform.

bool is_on_free_store (void) const function
Returns true if memory for the Point has been dynamically allocated on the free store, i.e., if the Point has been created using create_new<Point>(). See Point Reference; Constructors and Setting Functions.

bool is_on_plane (const Plane& p) const function
Returns true, if the Point lies on the Plane p, otherwise false.

Planes are conceived of as having infinite extension, so while the Point C in [next figure] does not lie within the Rectangle r, it does lie on q, so C.is_on_plane(q) returns true.1

          Point P(1, 1, 1);
          Rectangle r(P, 4, 4, 20, 45, 35);
          Plane q = r.get_plane();
          Point A(2, 0, 2);
          Point B(2, 1.64143, 2);
          Point C(0.355028, 2.2185, 6.48628);
          cout << A.is_on_plane(q);
          -| 0
          cout << B.is_on_plane(q);
          -| 1
          cout << "C.is_on_plane(q)";
          -| 1

[Figure 80. Not displayed.]

Fig. 80.

bool is_in_triangle (const Point& p0, const Point& p1, const Point& p2, [bool verbose = false, [bool test_points = true]]) const function
Returns true, if *this lies within the triangle determined by the three Point arguments, otherwise false.

If the code calling is_in_triangle() has ensured that p_0, p_1, and p_2 determine a plane, i.e., that they are not colinear, and that *this lies in that plane, then false can be passed to is_in_triangle() as its test_points argument.

If the verbose argument is true, information resulting from the execution of the function are printed to standard output or standard error.

This function is needed for determining whether a line intersects with a polygon.


  1. It's unlikely that Points will lie on a Plane, unless the user constructs the case specially. In [next figure] , the coordinates for B and C were found by using Plane::intersection_point(). See Planes; Intersections.